Water flow rate (or pressure) drop question

In summary, the conversation discusses a possible decrease in water flow or pressure on the first floor of a two-family house after a cracked pipe was replaced with a larger one on the second floor. The conversation suggests checking for debris and other blockages as well as considering the effects of friction and pipe size on water flow and pressure. It is also mentioned that the meters on each floor only measure the total flow and do not regulate it.
  • #1
Sintax668
5
0
Hi, I'm not sure if I'm posting in the right spot but I'm going to guess this is an easy question for you all. I'm going to give as much detail as I can, maybe too much..

My 2 family house condo has a single 2" or 3" water supply from the street. It is split to supply the first floor and second floor. Until recently, the split to each floor stepped down to a 1/2" copper pipe, a section of the upstairs neighbors pipe cracked, it was replaced with 3/4" flexible pipe. On the first floor, I noticed an drop in water flow (or pressure, not sure but, the water comes out of the shower slower so I think flow).

There are water meters for each floor, after the split but before the step to 1/2" and 3/4 pipe.

A few question please, If the pipe size is different for each floor, is the flow/pressure affected?

If there is no demand on the second floor(3/4 pipe) will the flow/pressure increase on the first flow? (I assume no because of the meters, they wouldn't allow water to flow back and worth,- this may also lead to the answer to the first question, yes, the larger pipe will "steal" flow rate or pressure?)

I really hope my questions are clear. Ill provide any more information if needed.

Thanks In advance, SinTax
 
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  • #2
A change in pressure will change the flow and vice versa. Since the main supply is so large relative to the branches it is more likely something changed other than branch pipe size. You might look at the valves near and at the meters to assure one was not left partially closed. Even though your half was not repaired, valves may have been closed and not fully reopened. Also debris/rust may have been disloged and clogged the screen in your shower head.

Good luck!
 
  • #3
The pipe to the second flow will steal flow/pressure from the first floor only if water is flowing to the 2nd floor. The pipe to the first floor will steal flow/pressure form the second floor only if water is flowing to the 1st floor.

Chet
 
  • #4
Montoyas and Chet, thanks for replying. I'm going to check everything you've suggested.
 
  • #5
I looked at the meters (Badger RTR model 25), if I'm reading the dial correctly, the second floor reads, .95 cubic meters the first floor reads .77 cubic meters

Does this mean anything to you guys? I don't have the readings prior to the work being done. I am hoping these numbers can show a higher flow or pressure to the 2nd floor. I'm not sure if that would cause the first floor to drop in pressure.
 
  • #6
Ok sorry, it's cubic feet and the needle indicates %of ten gallons. Not flow or pressure.
 
  • #7
All else being equal, if they didn't change your pipe size, or the connecting pipe between the main and your piping, you should not see a difference in pressure than previously. Similar to Chestermiller's point, the only difference you might see would be if both yourself and your neighbor were running water at the same time. It is possible that the larger pipe in their walls result in a lower back-pressure than your system which would result in them taking a larger share of the water than previously while both systems are running. However given that they are above you, and that I can't imagine they replaced all of their piping, I find it unlikely that it would be noticeable.

More likely your showerhead has scaling/buildup or there are additional blockages/leaks in the existing piping.

Meters are don't regulate flow, they measure it.
 
  • #8
I was thinking the meter would show flow rate or pressure. What I am seeing happened right after the work was done. This is why I think it's related to the pipe diameter change caused it. But the replies to my post make sense. I'll check for debris since that's l I can really do.

No work was done to pipes in the walls. were able to see all the new pipe.

Thanks again for responding. I'll post anything I find. If you have any other thoughts or questions that may help determin an answer, please let me know.
 
  • #9
The larger pipe to their side could result in additional flow due to reduced friction. This increased flow rate would be balanced by slightly higher losses in the main pipe, which could potentially drop the pressure going to your floor.

But realistically, a small section of 3/4" pipe vs 1/2" is not going to make a noticeable difference...

Nope, those meters basically just read the total flow that has gone through them so that utility companies can manage water usage (and billing!)
 

1. What causes a drop in water flow rate?

There are several factors that can cause a drop in water flow rate, including clogs or blockages in the pipes, a decrease in water pressure from the source, or a malfunctioning pump or valve. Other potential causes include leaks, air pockets in the pipes, or a buildup of sediment or debris in the pipes.

2. How can I measure the water flow rate?

The water flow rate can be measured using a flow meter, which is a device that measures the volume of water passing through a specific point in a given amount of time. There are different types of flow meters, such as turbine, electromagnetic, and ultrasonic, that use various methods to measure the flow rate. Alternatively, you can also calculate the flow rate by measuring the volume of water passing through a point in a given amount of time using a measuring cup or bucket.

3. Is a drop in water flow rate a cause for concern?

It depends on the severity and duration of the drop in water flow rate. If it is a temporary issue caused by a clog or air pocket, it may not be a major concern. However, if the flow rate consistently remains low, it could be a sign of a larger issue that requires attention. A significant and sudden drop in water flow rate could also indicate a burst or broken pipe, which should be addressed immediately.

4. How can I increase the water flow rate?

The solution to increasing water flow rate will depend on the underlying cause. If the issue is a clog or blockage, it can often be resolved by using a plumbing snake or chemical drain cleaner. If the problem is a decrease in water pressure from the source, you may need to contact your water provider to address the issue. If it is a malfunctioning pump or valve, a professional plumber may need to repair or replace the equipment.

5. How can I prevent a drop in water flow rate?

To prevent a drop in water flow rate, it is essential to regularly maintain your plumbing system. This includes regularly cleaning and clearing out any clogs or blockages, checking for and repairing any leaks, and ensuring that your pipes are free from sediment or debris buildup. It is also crucial to address any issues with your water source or equipment promptly to prevent a drop in water flow rate.

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